When separating gaseous pollutants from process gases, such as flue gases from a coal-fired or oil-fired power plant, a method is frequently used in which a lime-containing absorbent material is introduced into the process gases to react with the gaseous pollutants so as to allow removal thereof. When the absorbent material reacts with the gaseous pollutants, the gaseous pollutants are converted chemically or physically into dust, which is then separated in a filter from the remaining gases. WO 96/16722 discloses a method, in which lime-containing dust is mixed with water in a mixer and then introduced into a contact reactor to react with gaseous pollutants in a flue gas flowing therethrough. The resultant dust including the chemically or physically converted gaseous pollutants is then separated in a filter, circulated to the mixer, and mixed again with water to be reintroduced into the contact reactor to repeat the process.
It has now been found that the mixing of water and dust in the mixer is sometimes less efficient, which results in less efficient removal of gaseous pollutants from the process gases.